This filter should be configured with the name envoy.filters.http.header_to_metadata.

This filter is configured with rules that will be matched against requests and responses.
Each rule has a header and can be triggered either when the header is present or missing. When
a rule is triggered, dynamic metadata will be added based on the configuration of the rule.
The metadata can then be used for load balancing decisions, consumed from logs, etc.

A typical use case for this filter is to dynamically match requests with load balancer
subsets. For this, a given header’s value would be extracted and attached to the request
as dynamic metadata which would then be used to match a subset of endpoints.

This would then allow requests with the x-version header set to be matched against
endpoints with the corresponding version. Whereas requests with that header missing
would be matched with the default endpoints.